The exhaust system of a diesel engine may be equipped with a trap to separate particulates from the engine exhaust gases and thereby reduce emission of particulates into the atmosphere. Such a trap must be regenerated periodically.
Some proposals for trap regeneration involve use of an additive in the fuel consumed by the engine. When the additive passes to the trap in the engine exhaust gases, it catalyzes combustion of the particulates in the trap and thereby facilitates regeneration of the trap.